The present present invention relates to actuators for clutches which couple an engine to a drive train and, more particularly, to a hydraulic actuator of adjustable character.
Automobile and other vehicular and automotive racing imposes severe demands upon drive train components because of the speed and high dynamic forces to which the components are exposed. For these reasons, automotive racing equipment must be designed for extreme lightness yet with sufficient strength for surviving under the most grueling conditions involving high angular velocities and angular acceleration, high temperatures, and high forces. In coupling engines to transmissions in racing automobiles, it is desirable to be able to actuate the clutch by hydraulic means in order to dispense with the usual actuating linkage, which is both cumbersome and exposed to damage from being hit with flying objects. Also, racing equipment desirably should be easy to install and permit replacement and installation in a minimum of time, such as when a transmission must be replaced within the least possible time. However, the use of hydraulic actuators presents a secondary problem of providing assured means of spacing a clutch-actuating mechanism in precise relationship to the clutch which it is to operate. This is complicated because there are many different kinds of engine and transmission combinations which have different spacings. In order to adapt a racing clutch to various of these combinations, heretofore it has been necessary to add spacers, shims or otherwise to reconfigure an installation on a custom basis. It has been proposed to utilize hydraulic clutch actuators which utilize a piston arrangement for permitting the piston to accommodate various possible spacings for a specific installation but typical of these designs is the requirement that the actuating component bear at all times against a throw-out bearing. This latter configuration has been termed self-adjusting but is, in fact, not truly self-adjusting but instead designed for permitting extraordinary piston travel, which can compromise strength as well as also being undesirable because the bearing is exposed to certain pressure at all times with consequent wear and loading upon the rotating components.
It is much more desirable if a hydraulic clutch actuator can be of a truly adjustable nature, i.e., may be provided with a disengagement position which is in precise proximity to clutch-operating components but will not actually contact or engage same until the driver, by pedal actuation, pauses in hydraulic engagement of the clutch.
In general, prior art hydraulic clutch actuators have been extremely difficult to install and remove, requiring either a complicated procedure and extensive time to change the clutch assembly and its actuator, which time is critical if a failure should occur during a race or in other circumstances where the components must be changed prior to resuming racing.
Accordingly, among the several objects of the present invention may be noted the provision of a coaxial adjustable hydraulic clutch actuator for automotive racing which can be adjusted without resort to spacers or other shimming procedures, to provide for precise placement of the clutch and its associated actuating components; which can be utilized with a wide variety of engine, clutch and transmission combinations; which is extremely easy to install and to adjust; which, when so adjusted, does not load or otherwise apply pressure to a throw-out bearing when the clutch is not being actuated which can be installed without modification of an engine's flywheel bell-housing; which physically retracts a throw-out bearing from contact with clutch actuator fingers when the clutch is not being actuated for disengagement; which is extremely compact and lightweight without compromise of strength or reliability; which is of precision character; yet is extremely economically constructed without compromise of high performance and longevity in use providing assurance against failure during use, as during a race; which can be used with a variety of different hydraulic master cylinder types; which can be transferred from one vehicle or transmission to another without damage or replacement of parts or hydraulic lines; which also provides a function of retaining a transmission input shaft bearing; which can be adjusted after it is already installed; which can be readjusted at any time quickly and easily; which includes means for keeping dirt or other other contaminants out of the operating parts thereof; which provides for extremely quick and easy "bleeding".
Briefly, a coaxial adjustable hydraulic clutch actuator of the invention is used with an automotive transmission and clutch, as in a racing vehicle for coupling power from the engine to the transmission, the transmission having a power input shaft and the transmission having actuating elements, the engine and transmission being joined by a bell housing, the actuator comprising a base housing providing means for retaining a bearing of the input shaft, a sleeve extending forwardly from the base housing with the input shaft extending coaxially through the sleeve, a piston fitted coaxially within the sleeve and providing between the piston and sleeve an annular chamber, both the piston and sleeve being coaxial to the input shaft, means for supplying hydraulic fluid under pressure to the chamber from exteriorly of the bell housing, a clutch actuating bearing carried coaxially by the piston for being driven into throw-out engagement with the clutch actuating elements by movement of the piston in response to said hydraulic fluid pressure for clutch actuating operation, means for resiliently urging the piston toward the base housing for normally maintaining the actuating bearing in a disengaged position, and means carried by the base housing for selectively adjusting the axial position of the actuating bearing in precise disengaged position relative to the clutch actuating elements.
Other objects and features will be in part apparent and in part pointed out below.